RFR: 8224980: FLAG_SET_ERGO silently ignores invalid values [v4]

[Ioi Lam]

> Clarify the `FLAG_SET_ERGO` API - the caller must ensure that a valid value is passed. Added an assert to check this.
> 
> Fixed two issues found by the assert:
> 
> - `NonNMethodCodeHeapSize`
> - `XXXThreshold` and `XXXNotifyFreqLog` flags in `CompilerConfig::set_compilation_policy_flags()`

Ioi Lam has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Merge branch 'master' into 8224980-FLAG_SET_ERGO-ignores-invalid-values
 - @dholmes-ora suggestion
 - @dholmes-ora comment - make sure errors are printed for FLAG_SET_ERGO
 - 8224980: FLAG_SET_ERGO silently ignores invalid values

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/12549/files
  - new: https://git.openjdk.org/jdk/pull/12549/files/8cf4b6e3..cfc685f4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12549&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12549&range=02-03

  Stats: 7004 lines in 229 files changed: 3490 ins; 2392 del; 1122 mod
  Patch: https://git.openjdk.org/jdk/pull/12549.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12549/head:pull/12549

PR: https://git.openjdk.org/jdk/pull/12549